Ultrasonic Flow Meter Explained | Working Principles

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⌚Timestamps:
00:00 - Intro
00:54 - Ultrasonic flow meter
01:20 - Physical principles
02:00 - Mechanical principles
02:49 - Electrical principles
03:16 - Dynamics
05:16 - Design considerations
06:40 - Applications

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There are many types of process flow meters:
- Coriolis mass flow meters;
- Positive displacement flow meters, such as turbine meters;
- Volumetric flow meters, like the ultrasonic flow meter, just to name a few.

Each type of flow meter operates on different physical, mechanical, and electrical principles.

In this video, we will explore the working principles for Ultrasonic flow meters. We will demonstrate how a simple physical property, sound, can be used to measure the rate of flow of a fluid moving in a pipe.

Ultrasonic flow meters measure the volumetric flow of the fluid, that is, the number of gallons or liters per unit time.

Ultrasonic flow meters require the use and understanding of some basic physical, mechanical and electrical principles that allow ultrasonic flow meters to accurately measure flow rate over a wide range of flow conditions.

Here are a few examples of using basic physical, mechanical, and electrical principles to measure the flow rate using an ultrasonic flow meter:

1) When fluid flows through a pipe, it flows in one direction at a velocity that is influenced by many factors, such as temperature, pressure, fluid viscosity, and pipe size.

2) Sound waves move through a fluid based on the transmission of vibrations through the fluid. These mechanical oscillations between molecules of the flowing fluid are passed to adjacent molecules, thereby transferring the wave to those adjacent molecules.

3) An ultrasonic flow meter generates sound waves using a rapidly vibrating piezoelectric crystal. These special ceramic crystals deform when an electric current is applied. By rapidly changing the electrical signal, the crystal will deform in one direction, and then in the other, causing a high-frequency wave to be generated.

An ultrasonic flow meter consists of at least one sensor and transducer pair. Each member of the pair can act both as a transmitter and a receiver.

- When in transmit mode, an oscillating electrical current creates a vibration in the piezoelectric crystal, and an ultrasonic wave is sent through the flowing fluid.

- When in receive mode, an ultrasonic wave passing through the fluid creates vibration in the piezoelectric crystal, and an electrical impulse is generated.

A pulse that travels from the upstream element to the downstream element, or with the flow, takes less time to make the trip than the pulse returning in the opposite direction, or against the flow. The difference in this time of flight between the two pulses is directly proportional to the flow velocity.

Since the volumetric flow rate is equal to velocity times the cross-sectional area of the pipe, which is fixed at the flow meter, this measurement yields the flow rate. This type of ultrasonic flow meter is appropriately named a time of flight flow meter.

In order to eliminate differences in the flow profile across the pipe, additional pairs of sensors are added to ensure an accurate measurement. Each pair of transmitter and receiver forms what is called a chord.

There are many different ways that the sensors are mounted in a time of flight ultrasonic flow meter.

- The sound wave pulses can travel directly from transmitter to receiver or the pipe wall can be used to reflect the sound waves.

- The sensors can be wetted, or built into the wall of the flow meter such that the sensors contact the fluid. Or the sensors can be strapped to the exterior of the pipe, where the sensors do not contact the fluid. The non-contact sensors are not quite as accurate.

Ultrasonic flow meters are an excellent choice for high-pressure, high-flow applications.

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#RealPars #UltrasonicFlowMeter #Sensor

[mohammedfatehkhan]

I was literally waiting for an ultrasonic flowmeter video.
Thanks realspars.

[alikoohi]

Great video...Can you make such an informative video on multi phase flow metering (with electrode and gamma ray source) principles??

[cck]

As usual excellent work. Can anyone tell please:
In which case, (for gases) we have to measure " mass flow rate" and in which case we will have to measure "volumetric flow rate"?
Thanks.

[MrWaalkman]

Ultrasonic flowmeters have one outstanding advantage in that you can temporarily mount them to existing pipes. This means that you can make measurements on all of your piping with just one meter. This saves a ton of money compared to installing a flowmeter per pipe.

The downside is that (in my experience) the external ultrasonic flowmeters are a bit finicky to set up. But that can be said for a number of flowmeters. When it comes to metering, there are lies, damn lies, and flowmeters.

And ultrasonic flowmeters also require 10x - 15x of straight pipe before the flowmeter and 5x of straight pipe past it. But this is a typical requirement for most other types of flowmeters as well.

What this means is that if your pipe is 2" in diameter, then you will need 20" to 30" of straight pipe ahead of the meter, and 10" past it. Not a big deal when your pipe diameter is small, but try it on some 60" pipes (ductwork) sometime. :)

[DesignDepartment-rc]

Its Great video, more informative ..we need paint flow detect device. We take trail on Keyence FD_Q, it sense hardener and thinner only. Paint flow quantity not detect. Pls suggest any other flow that's sense flow quantity & control flows of paint.

[jonwatson]

You seem to suggest that turbine meters are positive displacement. They are not. They are inferential meters or velocity meters
They usually have a limited viscosity range enhanced with helical rather than straight blades.
Ultrasonic meters, multichord, can handle fluids with viscosities as high as 4000 cst.
What you didn't explore but rather simply brushed over to say this was why you had multichord Meyers, I'd that the sound wave transits from transmitter to receiver and is influenced by the fluid velocity. Should that not be " mean fluid velocity"?.
It would have been helpful to. Explore the relationship between the measured transit time difference and laminar flows, transitional flows and turbulent flows.i would have expected to that swirl would have some effect. Not discussed.
However, a good basic explanation. Tks.

[박시언-or]

I enjoyed the video. I have a question.
Looking at the path that ultrasound crosses, it seems to pierce the wall twice in the middle. By the way, can ultrasound penetrate a blocked wall?
My experiment showed that ultrasound couldn't penetrate the wall.
So I wonder if ultrasound can pass through obstacles.

[CALeftHander]

Perfect educational video for me. Thank you for sharing.

[_of_]

Whats a good one for reading water consumption wireless?

[pavunumuthu]

Very information video respect full real pars. Ultrasonic video

[neptune]

I see you reply to almost every comment so I'm going to take my chances and ask you something. I'm learning a lot from your videos but I am still not sure what is the best type of flow meter is for my case and I would appreciate if you could help me.

I want to measure the volumetric flow of water through a 3/4 or 1" pipe for a potable water vending machine I am planning to build. See Watermill Express as an example. Which type of flow meter do you think would be the best choice for this case? I know turbine flow meters would probably work well but (leaving the cost factor aside for a moment) is the ultrasonic even better? Is it more accurate?

[firedon]

how would you compare these to thermal mass flow meters for compressed air flow measurement?

[sdykhg]

Can i get a video on how analog input are processed in PLC analog card.??

[JorgeFlores-mjrl]

Are ultrasonic meters able to flow bidirectionally?

[TrungLinhNguyennn]

Very useful clip, thank you for sharing

[asadiqbal]

very informative thanks real pars make more videos on instrumentations

[danieldapilma]

Great video. Very informative and easy to understand. You have gained a subscriber!

[sinanartemis]

hi why dont you make a pcs7 course on siemens

[nicolasriart]

how do ultrasonic flow meters perform on curved pipes?

[logeshjeeva]

Proud to be your subscriber.Thanks for this video.. 👍 Grabbing ease of learning in your videos..